System for providing automatic voice messaging in a digital network environment

ABSTRACT

The present invention describes an automatic voice messaging system for use in a telephone network having a calling station connectible to a first switch and a called station connectible to a second switch, with the first and second switches connected by a digital serial link. The voice messaging system preferably comprises an interface, a detection circuit, a speech circuit and a control circuit. The interface monitors signals on the digital serial link. The detection circuitry is connected to the interface for detecting busy or ring/no answer conditions at the called station upon call initiation to the called station from the calling station, and for detecting receipt of a predetermined code from the calling station indicating that the caller desires to leave a message for the called station. The speech circuit is also connected to the interface for issuing a predetermined prompt to a user of the calling station. The control circuit is connected to the detection circuit and the speech circuit for controlling the speech circuit to issue one of the predetermined prompts to the calling station upon detection of a busy or ring/no answer condition by the detection circuit, and for thereafter connecting the calling station to a host computer upon detection of the predetermined code by the detection circuit to enable the user to record at the host computer a message for the called station.

This application is a continuation in part of prior co-pendingapplication Ser. No. 07/342,480, filed Apr. 24, 1989, now U.S. Pat. No.4,901,341, which is a continuation in part of prior application Ser. No.07/209,891, filed June 22, 1988, now U.S. Pat. No. 4,825.460.

TECHNICAL FIELD

The present invention relates to voice message storage and forwardmethods and systems and more particularly to an automatic voicemessaging system for use in connection with a digital telephone network.

BACKGROUND OF THE INVENTION

It is known in the prior art to carry telephone calls between localtelephone operating companies through the AT&T network or through one ormore independent inter-exchange carriers such as MCI or Sprint. Thelocal telephone operating companies operate within a so-called localaccess and transport area (LATA). When a long distance call is dialed,the call is usually transmitted through an operating company centraloffice to a point of termination in the originating LATA at which it ispicked up by the inter-exchange carrier and passed by that carrier on toa termination point in a distant LATA. Upon reaching the destinationLATA, the call is then transferred by the inter exchange carrier to thelocal operating company central office within that LATA for ultimateconnection to the original called station therein. Typically, thetermination points of each LATA include suitable switching circuits,e.g., an access tandem, that are interconnected by a digital seriallink. Such digital links are also presently used to interconnectvirtually all central offices as well as to interconnect operatingcompany switching networks to one or more cell site control switches ofa mobile telephone network.

It is also known in the prior art to provide "automatic voice messaging"where, upon the occurrence of a busy/ring-no-answer condition at acalled station, the user of the calling station can be connected to avoice message facility for recording a voice message for subsequentdelivery to the called station. Automatic voice messaging has notheretofore been integrated into a telephone network having multipledigital links.

It would therefore be desirable to provide automatic voice messaging ina telephone system having various types of switching circuits that areinterconnected via digital serial links.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide automatic voicemessaging and related caller-controlled applications in digitaltelephone network.

It is yet another object of the present invention to provide anautomatic voice messaging system that is capable of interfacing to andigital communications link located between a pair of switchingcircuits.

It is another object of the invention to provide automatic voicemessaging in a cellular telephone network.

It is a further object of the present invention to use in-band and outof band signaling techniques in connection with the providing ofautomatic voice messaging services in a digital network environment.

These and other objects of the invention are achieved in a preferredembodiment of the invention wherein an automatic voice messaging systemis provided for use in a telephone network having a calling stationconnectible to a first switch and a called station connectible to asecond switch, with the first and second switch means connected by adigital communication link. Preferably, the link is a T-1 span line overwhich in-band DTMF or FSK signals are provided. The link may alsosupport out-of band signaling such as signaling provided under thecommon channel signaling ("SS7") protocol. In one embodiment, both thefirst and second switches are access tandems located at terminationpoints between two LATAs. Alternatively, the first switch is an accesstandem and the second switch is a cellular tandem or cell sitecontroller for a mobile telephone system. Such a configurationfacilitates the provision of automatic voice messaging in a cellularnetwork. The first and second switches could alternatively be twooperating company central offices, or any other switching devicesinterconnected by a communication link that supports digital signaling.

The voice messaging system preferably comprises a "voice storage unit"or host computer, an interface means, a detection means, speech meansand control means. The host computer stores voice messages. Theinterface means monitors signals on the digital serial link. If the linkis a conventional T-1 span line, the interface means includesappropriate T-1 interface circuits. The detection means is connected tothe interface means preferably for detecting busy or ring/no answerconditions at the called station upon call initiation to the calledstation from the calling station, and for detecting receipt of apredetermined code from the calling station preferably indicating thatthe caller at the calling station desires to leave a message for thecalled station. The speech means is likewise connected to the interfacemeans for issuing a predetermined prompt to the caller at the callingstation. The control means is connected to the detection means and thespeech means for controlling the speech means to issue the predeterminedprompt to the caller upon detection of a busy or ring/no answercondition by the detection means, and for thereafter connecting thecalling station to a host computer upon detection of the predeterminedcode to thereby enable the caller to record, at the host computer, amessage for the called station. The host computer is directly connectedto the interface means or, alternatively, is connected to other portionsof the network via one or more trunks.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more completed understanding of the present invention and theadvantages thereof, reference is now made to the following Descriptiontaken in conjunction with the accompanying Drawings in which:

FIG. 1 is a simplified block diagram of a prior line interface unit foran analog environment as described in U.S. Pat. No. 4,825,460 foroffering the automatic voice messaging service to a calling station userand connecting the calling station to a voice message facility upon theuser's acceptance of the service;

FIG. 2 is a block diagram of a digital telephone network in which, theautomatic voice messaging system of the present invention is preferablyincorporated; and

FIG. 3 is a detailed block diagram of the preferred embodiment of theautomatic voice messaging system of FIG. 2.

DETAILED DESCRIPTION

Referring now to the drawings wherein like reference numerals designatelike or similar parts throughout the several figures, FIG. 1 is a lineinterface unit 200 for providing enhanced control of receipt anddelivery of voice messages over a telephone system having a voicemessage facility 18 connectible to at least one calling station 12 and acalled station 16 via a central office 14. The line interface unit 200,described in U.S. Pat. No. 4,825,460, advantageously provides certaincall intercept and message prompting operations in a standalone unitboth externally to the calling station 12 and the voice message facility18. The interface unit may be located adjacent to the calling station oron the input side of the central office switching eguipment.

As seen in FIG. 1, and as more particularly described in U.S. Pat. No.4,825,460, the line interface unit 200 comprises a plurality offunctional modules including first, second and third switches 202, 204and 206, respectively, DTMF detector circuits 208a and 208b, a speechcircuit 210, a speed-dial circuit 212, a coin detect circuit 214, a callprogress detector circuit 216, a control circuit 218, a calling stationmonitor circuit 224 and a central office monitor circuit 226. Thecontrol circuit 218 is preferably a microprocessor based controllerhaving suitable control programs for effecting the operations describedbelow. The control circuit 218 is connected to control the first, secondand third switches 202, 204 and 206, as well as the speech circuit 210and the speed dial circuit 212. The speech circuit 210, the speed dialcircuit 212 and/or the control circuit 218 may be shared by a pluralityof line interface units each having the disclosed switching andmonitoring components.

As described in U.S. Pat. No. 4,825,460, each of the first and secondswitches are a double pole, double-throw switch located in the tip andring lines 220 and 222 between the calling station 12 and the centraloffice 14. In particular, the first switch 202 is connected to thecalling station 12 in the tip and ring lines 220 and 222 and the secondswitch 204 is connected to the central office 14 in the tip and ringlines. Each of the switches 202 and 204 have first and second positionssuch that signals on the tip and ring lines 220 and 222 are connecteddirectly between the calling station 12 and the central office 14 wheneach of these switches are in the first position. The unit is thus"idle" when the switch contacts of the first and second switches 202 and204 are in their first position. However, the line interface unit 200communicates directly with the calling station 12 when the first switch202 is switched from its first position to its second position.Likewise, the line interface unit communicates directly with the centraloffice 14 when the second switch 204 is switched from its first positionto its second position. The unit 200 thus communicates with both thecalling station 12 and the central office 14 when the switch contacts ofswitches 202 and 204 are activated to the second positions. When bothswitches are in their second position, a small amount of crosstalkbetween the switches 202 and 204 exists and is advantageously used bythe interface unit 200 for the purpose described below. Switching of thesecond switch 204 between its first and second positions automaticallydisconnects the calling station from the central office 14 and reordersdialtone to the line interface unit 200.

As noted above, the line interface unit 200 also includes the speechcircuit 210 for issuing one or more predetermined (English or bilingual)prompts to the caller at the calling station 12. For example, the speechcircuit is controlled by the control circuit 218 to issue a prompt todetermine whether the caller at the calling station desires to leavevoice message for a called station. If the caller desires to leave avoice message, the control circuit 218 operates to control thespeed-dial circuit 212 for speed dialing the voice message facility 18.The control of this operation is effected through sensing of varioussignals by the line monitor circuits 224 and 226.

In particular, the calling station monitor 224 is connected across thetip and ring lines 220 and 222 adjacent the calling station side of theunit 200. Likewise, the central office monitor circuit 226 is connectedacross the tip and ring lines adjacent to the central office side of theinterface unit 200. The calling station monitor 224 monitors the tip andring lines for coin detect signals (which are processed by the coindetect circuit 214) or receipt of a predetermined DTMF signal (e.g., a"#" key) from the calling station (which is processed by the DTMFdetector circuit 208a). The central office station monitor 226 monitorsthe tip and ring lines for detecting a predetermined condition at thecalled station (e.g., a busy/no answer condition) upon call initiationto the called station. Central office monitor circuit 226 also monitorsthe tip and ring lines for detecting receipt of standard or non standardDTMF signaling which is then processed by the DTMF detected circuit208b. The control circuit 218 includes a switch 219 for selectivelyswitching the outputs of the DTMF detector circuits 208a and 208b to thecontrol circuit 218.

Although not meant to be limiting, preferably the DTMF detector circuit208a senses receipt (over the calling station monitor 224) of a standardDTMF signal indicating that the caller at the calling station desires toleave a voice message for the called station. Alternatively, the callercan deposit additional coinage or pull a credit card through acardreader to indicate his/her intention to record a voice message. TheDTMF detector circuit 208b senses receipt (over the central officemonitor 226) of a non standard DTMF signal from the voice messagefacility following the speed-dialing thereto as will be described inmore detail below.

The third switch 206 of the line interface unit is connected between thering line 222 and ground for the purpose of generating a ground startafter the speed dial circuit 212 has speed-dialed the voice messagefacility. This ground start is required to enable the interface unit 200to complete a connection to the voice message facility 18 through thecentral office without the caller having to deposit additional coinagein the paystation. As also seen in FIG. 1, the line interface unit 200includes the coin detect circuit 214 for detecting receipt of coinage inthe paystation. Coin detect circuit 214 is preferably coupled to thecontrol circuit 218 to provide a running total of all coins deposited inthe calling station over a predetermined time. Moreover, the controlcircuit 218 can be remotely reprogrammed (e.g., to change the prompt,the language of the prompt, the calling station identification or thenumber of unanswered rings at the called station which will initiate acall default) through DTMF signaling from a host or handset. To effectreprogramming, the second switch 204 is switched to its second positionand the parameter information is down loaded to the microprocessor.

In operation, the control circuit 218 responds to a busy/no answercondition at the called station (following call initiation thereto) forswitching the first switch 202 from its first position to its secondposition. This operation disconnects the calling station handset fromthe central office and connects the speech circuit 210 to the callingstation 12 for issuing the prompt to determine if the caller desires toleave a voice message. After the prompt is issued, the calling stationmonitor circuit 224 waits for receipt of the DTMF signal from thecalling station (or, alternatively, waits for receipt of additionalcoinage). If no DTMF signal is received (i.e., if the caller does notdesire to leave a voice message), the unit 200 remains idle. However,upon detection of the DTMF signal by the DTMF detector circuit 208a (orthe detection of additional coinage by coin detector 214 as the case maybe), the control circuit 218 responds by switching the second switch 204from its first position to its second position. This switching reordersdialtone and connects the speed-dial circuit 212 to the central office14 for dialing the voice message facility 18. The central office monitorcircuit 226 then waits for receipt of the DTMF signal from the voicemessage facility. The control circuit 218 then responds to detection ofthe DTMF signal by the DTMF detector circuit 208b for effecting a"handshake" to the voice message facility and then switching the firstand second switches 202 and 204 from their respective second positionsback to their respective first positions to thereby connect the callingstation 12 to the voice message facility 18.

As noted above, when the calling station 12 is a paystation, the lineinterface unit 200 must present a ground start to the central office 14in order to dial the voice message facility 18 without additionalcoinage. To this end, the control circuit 218 operates to activate thethird switch 206 connected between the ring line 222 and ground forgenerating a ground start after the voice message facility 18 has beendialed by the speed-dial circuit 212. This ground start is typicallyperformed immediately after the last digit of the voice message facilityis dialed by the speed-dial circuit and enables the interface unit tocomplete a connection to the message facility without the caller havingto deposit additional coinage. After the ground start, the controlcircuit 218 is responsive to receipt of the preferably non-standard DTMFsignal from the voice message facility 18 for switching the first andsecond switches from their respective second positions back to theirrespective first positions. This operation connects the callingpaystation to the voice message facility. The use of non-standard DTMFsignaling increases security of the transmissions between the callingstation and the voice message facility.

The line interface unit 200 provides a so called "voice over" operationwherein the caller at the calling station 12 is allowed to continue tomonitor the call progress (i.e., the ringing on the line) while beingprompted to leave a message. In this embodiment, the control circuit 218is responsive to a predetermined condition at the called station (e.g.,three (3) rings with no answer) for switching the first and secondswitches from their respective first positions to their respectivesecond positions. This operation connects the speech circuit 210 to thecalling station 12 for issuing the prompt while simultaneously enablingthe caller at the calling station to continue to monitor the progress ofthe call. After the prompt is issued during the voice over operation,the control circuit 218 is responsive to receipt of a DTMF signal fromthe calling station 12 for switching the second switch from its secondposition to its first position and then back to its second position.This operation reorders dialtone to the interface unit 200 and thenconnects the speed-dial circuit 212 to the central office for dialingthe voice message facility 18. After dialing the voice message facility,the control circuit is responsive to receipt of the DTMF signal from thevoice message facility for switching the first and second switches fromtheir respective second positions back to their respective firstpositions and thereby connect the calling station to the voice messagefacility.

Before the first and second switches are returned to their firstposition to connect the calling station to the voice message facility,the line interface unit 200 performs a "handshake" with the voicemessage facility 18. In particular, the control circuit 218 transmits apredetermined data string to the voice message facility 18. This datastring may have the following format --"#", "#", (10-digit number ofcalling station, "#", (1-digit activity code), "#", (called stationnumber), "#"--. The data string may also include a credit card number orother billing information. The "#" sign delimits the fields of the datastring. The activity code informs the voice message facility 18 or otherhost that an alternative prompt has been made (e.g., a bilingualprompt). Alternatively, the activity code is a special code indicatingthat connection is required to an alternate voice message facility, thatthe calling station includes a facsimile apparatus, that certain coinagehas been deposited or that certain keypad signals have been receivedindicating acceptance of the service. One or more of the "#" signs atthe beginning of the data string described above may alternatively benon-standard DTMF signaling (such as an "A") for increased security.When the voice message facility receives the data string, it transmitsan "acknowledge" signal (e.g., an "*") back to the unit or requestsretransmission if the data has not been received. Upon receipt of theacknowledge signal, the control circuit 218 switches the first andsecond switches back to their respective first positions.

The voice message facility may include access prevention circuitryand/or algorithms to prevent receipt and/or forwarding of voice messagesunless predetermined access codes are presented to the system. In thiscase, the data string from the interface unit 200 should then include apredetermined "key" that "unlocks" the voice message facility's accessprevention circuits and algorithms. According to the present invention,the "key" provided to unlock the voice message facility is preferablypart of the data string transmitted to the facility during the handshakeprocess. In particular, but without meant to be limiting, the "key"comprises three elements: the number of the calling station or "ANI", apredetermined number of digits representing the destination number, andsome billing information for use in billing the user of the callingstation for the caller controlled message delivery service. The accessprevention circuitry of the voice message facility is thenpre-programmed to search for a data string with these components. Theactual destination number is not relevant as long as the data stringincludes the proper number of digits for this number. If a data stringreceived by the message center does not include these components in therequired predetermined order and/or without the proper number ofexpected digits, no acknowledge signal is returned to the interface unitand the unit is disconnected from the message center. If the data stringincludes the proper "key," however, the voice message facility becomes"barrierless" to the voice message subsequently transmitted from thecalling station. The stored voice message can then be subsequentlyforwarded without input of the access codes normally required by thevoice mail system.

While in the preferred embodiment the line interface unit 200 is adaptedfor use with a single calling station, a plurality of calling stationsmay be selectively switched to a single interface unit. Moreover,although not discussed in detail, it should be appreciated that otherforms of signaling may be used in the invention. For example, thecontrol circuit 218 may include appropriate circuitry for processing FSKsignaling if desired. Further, the control circuit 218 of the lineinterface unit 200 may alternatively include appropriate software toperform automatic number identification ("ANI") following the caller'saffirmative decision to leave a voice message. This ANI function isadvantageous when the calling station and the called station areINTRALATA.

Referring now to FIG. 2, a block diagram is shown of a generic digitaltelephone network 250 in which an automatic voice message system isadvantageously provided according to the teachings of the presentinvention. The telephone network generally includes a first switch 252,a second switch 254, and a plurality of digital communications linksinterconnecting the first and second switches 252 and 254 and designatedby the reference numerals 256a-n. At least one digital link 256 ispreferably a high speed (1.544 MHz) T-1 span over which conventionalin-band signaling is provided in a serial fashion; of course, otherhigher speed links such as DS/3 or DS/4 can be used. Link 256,alternatively, is a high speed digital serial link over which digitalsignals are provided using out-of-band signaling with othercommunications protocols, such as X.25 or common channel signaling(SS7).

For purposes of generalizing the features of the invention, FIG. 2 showsa calling station 258 connected (or connectible via a central office orthe like) to the first switch 252 and a called station 259 connected (orconnectible) to the second switch 254. For the remainder of thediscussion, it is assumed that a call to the called station 259 isinitiated by a caller at the calling station 258. According to thepresent invention, an automatic voice messaging system 260 is placedacross or in a digital link 256 for enabling receipt and delivery ofvoice messages under the control and at the expense of the caller at thecalling station 258.

Without limiting the foregoing, the first and second switches 252 and254 are access tandems located at termination points between two LATAs.Alternatively, the first switch 252 is an access tandem and the secondswitch 254 is a cellular tandem or cell site controller for a mobiletelephone system. In this configuration, the network 250 is a cellulartelephone network. The first switch 252 may be an operating companycentral office while the second switch 254 is an access tandem. Thefirst and second switches can interconnect two central offices. Thefirst switch can be an IXC switching system and the second switch can bea cellular tandem or central office. Both switches may be cellulartandems or components of a cellular telephone system.

Referring now to FIG. 3, a detailed block diagram is shown of thepreferred embodiment of a digital caller-controlled automatic voicemessage system 260 for use in a digital network environment. System 260preferably includes an interface means including a plurality ofinterface circuits 262a-n each connected to a multiplexer 264. Themultiplexer includes a control bus connected to a control meanscomprising a processor 266, storage interface 268, storage device 270and input/output device 272. The processor is controlled in aconventional manner by suitable application programs stored in thestorage device 270. Input/output device is used to modify the systemoperation by entering suitable program commands to the control means.

The system 260 further includes a number of circuits for facilitatingthe intercept, prompting and redirect functions associated with theautomatic voice messaging service. A scanner circuit 274 is provided toidentify Feature Group D supervision or other similar informationdepending on the type of signaling used. A service circuit 276 includesall of the necessary call progress (busy/ring no answer) detectioncircuits, speech generation circuits, and service acceptance (e.g.,DTMF) detection circuits. The service circuit 276 also preferablyincludes appropriate circuitry for capturing ANI, DNI and billinginformation. A first communication interface 278 is provided to receive,interpret, format and transmit SS7 messages as will be described in moredetail below. The system preferably also includes a second communicationinterface 280 connected to a voice message facility platform 282. Theplatform 282 includes a billing computer and other appropriate devicesfor transaction processing and accounting purposes. The system 260advantageously includes its own dedicated voice storage unit 284 forstoring voice messages. A disk storage 286 is connected to the voicestorage unit 284. The voice message storage may take place either in thevoice storage unit or in the platform, as is appropriate, to facilitatesubsequent delivery.

Each of the circuits 274, 276, 278, 280 and 284 are connected to theprocessor 266 via the control bus 290. Input/output channel buses 292and 294 also interconnect these circuits to the multiplexer of theinterface means. Preferably, the interface means includes twenty eight(28) T-1 interface circuits, each of which is connected to two digitallinks. Each T-1 interface circuit includes first and second T-1interface circuits, with the first interface circuit connected to one ofthe digital links and the second interface circuit connected to theother digital link. The first and second digital links are thusconnectible to bypass their respective interface circuit if the thefirst and second T-1 interfaces are interconnected by means of a switchbetween the T-1 interfaces. Given this architecture, i.e., with 28 T-1spans each carrying twenty four (24) channels, the buses 292 and 294service 1344 channels.

In operation, the scanner 274, service circuit 276 and/or communicationsinterface 278 monitor the received signaling to determine the state ofthe call progress. Of course, the actual circuit used depends on thetype of signaling. If an SS7 protocol is used, communications interface278 monitors the line. If Feature Group D or other types of signalingare used, scanner 274 is used, and so forth. When call processing isrequired due to a busy or ring/no answer condition, the processor 266activates the service circuits 276 to thereby issue the prompt offeringand monitor the line for acceptance of the service. Processor 266 alsocontrols the circuit 276 to capture ANI, DNI and billing information. Ifthe service is accepted, the service circuit 276 notifies the processor266, which then controls the service circuit to issue appropriateprompts to the caller to instruct the caller to begin recording themessage. The message is then recorded by the voice storage unit 284, andthe processor controls the service circuit 276 to transfer the ANI, DNI,and billing information to the platform 282. Although not meant to belimiting, preferably voice messages are stored in the voice storage unit284 or its associated disk storage, while ANI, billing and othermanagement information reside in the platform 282.

For message delivery, the platform ships the message routing information(i.e., the ANI, etc.) back to the voice storage unit 284, and theprocessor 266 then locates an open channel on a link for outdialing tothe original called station. The service circuit then dials the call.When the call is placed, the scanner 274 watches the call states for onhook/off hook detection. If off-hook is detected, the service circuit276 issues a prompt announcing the message which is then delivered bythe voice storage unit 284. When the message is delivered, the processor266 notifies the platform and the routing information for the message isdeleted.

If desired, the system 260 is connectible to a remote host computer viaa communications interface which in turn is connected to the remote hostvia an RS-232 link or the like. This enables messages to be transferredto another location for the subsequent outdial attempts.

The system 260 described in FIG. 3 advantageously allows automatic voicemessaging and other related caller-controlled functions to be providedin many different types of applications. One such application is in thecellular communications environment. Referring simultaneously to FIGS. 2and 3, assume the caller at the calling station 258 attempts to call thecalled mobile station 259 but the call cannot be completed because thecalled party is on the phone or away from his/her car. The voice messagesystem 260 intercepts the call and offers to attempt to deliver (byexample) a one-minute message to the called station every ten minutesfor three hours, for a predetermined fee, to be billed to the callingparty. When the service is accepted, the system connects the caller tothe voice storage unit or other adjunct host computer which records themessage and billing information, makes the delivery attempts andmaintains accounting records. The operation is likewise available if thecalling party is the mobile station and the called party is, forexample, a residential phone or a business extension located behind aprivate branch exchange.

It should be appreciated by those skilled in the art that the specificembodiments disclosed above may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the invention as set forth in the appendedclaims.

What is claimed is:
 1. An automatic voice messaging system for use in atelephone network having a first switch means and a second switch meansconnected by a plurality of digital serial links, comprising:processormeans for controlling the operation of the voice messaging system; aplurality of interface circuits for interfacing to the digital seriallinks; a multiplexer connected to the plurality of interface circuitsand having an output bus, the multiplexer being controlled by theprocessor means to selectively connect telephone signals from thedigital serial links to the output bus; caller-controlled automaticvoice messaging service means connected to the output bus of themultiplexer and being controlled by the processor means for providingautomatic voice messaging for the plurality of digital links, theautomatic voice messaging service means comprising:means for detectingtelephone signals representing busy or ring/no answer conditions at acalled station upon call initiation to the called station by a caller ata calling station; means for informing the caller of availability ofautomatic voice messaging services; means for detecting receipt of apredetermined acceptance code from the calling station indicating thatthe caller desires to leave a message for the called station; means fordetermining ANI or billing information from the caller at the callingstation; storage means connectable to the multiplexer by the processormeans following receipt of the predetermined acceptance code forreceiving and storing a message for the called station, and for storingANI or billing information; means for signaling the called station;means for locating an open digital serial link and for connecting thesignaling means to the open digital serial link to signal the calledstation; and means responsive to the called station going off-hook fordelivering the message to the called station.
 2. The automatic voicemessaging system as described in claim 1 wherein the first switch meansis an access tandem and the second switch means is a cellular tandem fora mobile telephone system.
 3. The automatic voice messaging system asdescribed in claim 1 wherein the first switch means is a central officeand the second switch means is an access tandem.
 4. The automatic voicemessaging system as described in claim 1 wherein the first switch meansis switching system for an inter exchange carrier and the second switchmeans is an access tandem.
 5. The automatic voice messaging system asdescribed in claim 1 wherein the first switch means is a central officeand the second switch means is a central office.
 6. The automatic voicemessaging system as described in claim 1 wherein the first switch meansis a cellular tandem and the second switch means is cellular tandem. 7.The automatic voice messaging system as described in claim 1 wherein thefirst switch means is a central office and the second switch means is acellular tandem.
 8. The automatic voice messaging system as described inclaim 1 wherein the first switch means is a switching system for aninter exchange carrier and the second switch means is a cellular tandem.9. The automatic voice messaging system as described in claim 1 whereinthe first switch means is a switching system for an inter exchangecarrier and the second switch means is a central office.
 10. Theautomatic voice messaging system as described in claim 1 wherein thesignals on the digital serial link are in-band signals.
 11. Theautomatic voice messaging system as described in claim 1 wherein thesignals on the digital serial link are out-of-band signals.
 12. Theautomatic voice messaging system as described in claim 11 wherein theout of band signals are provided according to the common channelsignaling system No. 7 (SS7) protocol.